The importance of cyber security continues to increase as the use of computers continues to grow. Cyber security encompasses all aspects of protection of computer systems including theft of and damage to resources such as hardware, software, data and so on. Computer systems, and especially computer systems that provide services over public networks, can be the target of various attacks in which attempts to obtain unauthorized access to resources are made.
One type of attack is an enumeration attack. An enumeration attack is an attack in which an attacker makes a series of guesses and observes the system's response to determine if a guess was correct. The targeted computer system may inadvertently or deliberately provide information to illegitimate and legitimate actors about resources. For example, when erroneous credentials such as account identifier credentials and/or authenticating credentials are submitted, the targeted computer system may return a message that states that the credentials provided are invalid, thereby letting an attacker know that, for example, either a username or password is incorrect. Some known systems will identify what portion of the credentials are incorrect. For example, a system may provide an error message that states that a provided username is present on the system, thereby letting the attacker know that the username portion of the credentials is valid. The information obtained by the attacker can be used in other attacks that attempt to get enough information so that the attacker can acquire illegitimate access to the system.